Also set to appear is John Corvino, a philosophy professor at Michigan’s Wayne State University. He has written extensively about same-sex unions and is also gay.

Corvino welcomed the sit-down, hoping it will give those who oppose gay marriage “a better understanding of the reality of our lives … of our commitment and sacrifice and joy.”

Garlow will act as moderator and said he intends to ask both sides tough questions. He said he is prepared, however, to step out of that role briefly if he feels he needs to make a point.

The longtime preacher has said that he believes the move to allow same-sex marriage is part of a “radical homosexual agenda” aimed at derailing religious freedom and other fundamental rights in this country.

While Garlow has been dismissed by many of his critics as a voice of intolerance, he has reached out before to those with starkly opposing views. He once had an atheist speak at the church, along with a lesbian pastor.

“Even though I adamantly disagree with Gene Robinson, I respect him as a human being,” Garlow said.

The two men met more than a year ago. “I really find Jim to be a personable guy,” Robinson said.

In recent years, other megachurches tied to the evangelical movement have also staged high-profile events with unlikely guests.

Before the 2008 presidential election, then-candidate Obama appeared before the conservative congregation at Saddleback Church in Orange County to talk about global issues like AIDS and to answer questions about his own Christian faith.

The Rock Church in San Diego last month welcomed porn industry legend Ron Jeremy to its Sunday services as part of a church series that challenged attendees to follow Jesus’ teaching of unconditional love.